1. Field of the Invention
The present invention relates generally to structural engineering and design, and in particular, to a method, apparatus, and article of manufacture for determining wind load structure.
2. Description of the Related Art
Engineers must design structures to withstand the loading that the structure will experience. One of the more difficult loadings that the engineer must account for is the effect wind will have when interacting with the structure. Flowing air will create pressure, both positive and negative, when it encounters a structure and interacts with it. Flow patterns are determined by the shape of the structure, and direction that the flowing air comes from. Understanding these interactions and the behavior of the air when interacting with the structure is a complex and time consuming task. Engineers often must rely on expensive and time consuming physical testing for all but the most simple geometries. To better understand the problems of the prior art, a description of wind loads and prior art approaches to determining the effect of wind may be helpful.
When designing structures, structural engineers must account for the effect of different loads/forces that may affect the structure. Different loads/forces cause a structure to move in different ways. For example, gravity loads (e.g., people walking on a structure, furniture in/on a structure, etc.) create a downward load. Loads applied in a sideways orientation (parallel to the ground) may cause a structure to move laterally. Two movements require a structure to have lateral reinforcement: (1) seismic movement (i.e., ground movement); and (2) wind that creates loads causing a building to move laterally. Accordingly, an important consideration for structural engineers is to design a structure with appropriate lateral reinforcement to withstand the effect of wind loads.
Designing a structure to account for different loads is a time consuming aspect of an engineering workflow. Every type of structure is wind exposed. Further, many different load cases have to be considered (as the value and direction of wind may differ). Prior art systems often apply simplified methods to different structure types. In many products, some national codes provide requirements that are used. In other words, load cases are based on building codes promulgated by local jurisdictions. Such prior art methods may be partially automated but are limited to specific structures or geometry types. Further, prior art solutions are very often insufficient for complicated structures. More specifically, for a lot of structure types, the wind load is the most significant load type (e.g., buildings with broad roofs and walls, masts, truss towers, silos, etc.). If the structure consists of a normal shaped building (e.g., rectangular multi-story structure), the code may provide details regarding how to apply load (e.g., based on exposure class and a number of other factors). However, when the geometry is not regular, the engineer must manually determine how the wind will affect a structure (e.g., what happens with flow patterns, where is positive pressure created, where is negative pressure created, etc.). With complicated geometry, determining the different wind load cases can be expensive and difficult.
With complex structures that fall outside of the standard codes, engineers attempt to create various load cases and guestimate as best they can during the building design. This process involves the manual time consuming creation of load cases (e.g., based on many rules, guidelines, and building codes). Thereafter, a model is created. In practice, the load case and model creation may simplify the geometry thereby resulting in overloading or overlooking various aspects. An expensive and time-consuming wind tunnel study is then conducted. In this regard, a physical prototype may be constructed, access to a wind tunnel is required and needs to be paid for, results are analyzed, results are correlated with the design, and the analysis is then scaled in order to determine the loads that are applied to the structure. Accordingly, limitations of a real wind tunnel testing includes not only high costs but also a time consuming process. Further, in many cases, understanding wind loads effects is significant even in the early stage of design, and can drive design stages. Unfortunately, wind tunnel testing often occurs at the later stages of the design process.
In view of the above, prior art systems for determining and analyzing wind loads are time consuming, expensive, and prone to error based on the extensive manual calculations and analysis that are performed. Prior art systems fail to provide any automation, fail to provide flow analysis, and fail to use computational fluid dynamics in order to understand the effects of wind on a structure.